1. Field of the Invention
The invention relates to methods and apparatus for positioning an article on a support and, more particularly, for moving rotatable members, symmetrically disposed with respect to a predetermined location on the support, into engagement with the article to position the article in the predetermined location.
2. Description of the Prior Art
In the prior art, square electronic circuit substrates have been placed on a pedestal or support and positioned laterally thereon by moving pyramidal cavities toward the support, e.g., in the manner of R. Cross et al., technical digest, Vol. 40, Western Electric Co., New York (Oct. 1975) p. 7. A sloping side or adjacent sides of the cavity contact a side or adjacent sides of the substrate and force it to move laterally until opposite sides of the cavity contact opposite sides of the substrate. When this occurs, the substrate is located in its proper position and rotated so that its sides are parallel to the cavity walls.
The substrates are generally fabricated from hard materials, such as ceramics, by scribing and breaking procedures. This generates very sharp abrasive corners or edges on which the pyramidal cavities must act. Thus, the sides of the cavities wear rapidly even if they themselves are made of ceramic. The wear not only manifests itself as a change in the slope of the cavity walls and change in cavity size but as a ledge, formed around the inside of the cavity, which makes the cavity ineffective for the purposes intended.